Fiber optic networks generally include transceivers which generate and sense optical pulses, and a transmission medium which allows the optical pulses to travel between the transceivers. While a wide range of optical transmitters have been used, ones operating at the 850 nm (nanometer) and 1300 nm wavelength windows have become relatively popular. To allow a multimode optical fiber (MMF) to operate in both of these windows, manufacturers shift the bandwidth of MMF between two wavelength windows by changing the shape of the refractive index profile of an MMF fiber core. The parameter that generally describes the refractive index profile is the alpha parameter (α-parameter), and the refractive index profile is often referred to as the α-profile. Depending upon the shape of the refractive index profile, the usual result is a fiber with either high bandwidth at the 850 nm window with low bandwidth at the 1300 nm window, or low bandwidth at the 850 nm with high bandwidth at the 1300 nm window.
While it is possible to design a dual wavelength window fiber for high bandwidth within a certain window (e.g., high bandwidth at 850 nm and low bandwidth at 1300 nm), factors such as modal and chromatic dispersion can limit the performance of such a fiber. In systems utilizing Vertical Cavity Surface Emitting Laser (VCSEL) transceivers the bandwidth of the fiber may be increased by modifying the refractive index profile to compensate for modal and chromatic dispersions as described in U.S. Pat. No. 8,398,900 to Tudury et al., entitled “Self-Compensating Multi-Mode Fiber,” filed on Aug. 17, 2010, and incorporated herein by reference in its entirety, and in U.S. Pat. No. 8,483,534 to Tudury et al., entitled “Modified Refractive Index Profile for Low-Dispersion Multi-Mode Fiber, filed on Aug. 19, 2010, and incorporated herein by reference in its entirety. However, further modifications to the fiber to improve its performance are desired.